"Children" who are post-pubertal do not regard themselves as children. If anything, they are incomplete adults rather than children. Paradoxically, they possess the most potent capability of adulthood, the ability to reproduce, but in bodies which are not quite fully formed and with brains which are not yet completely developed.
Frequently, their bodies are extremely attractive, approximating to the "ideal" of their sex - slim, tall, shapely (as appropriate), with good skin and (as yet) unaffected by gravity or poor eating habits. Girls typically achieve maturity perhaps one and a half to two years earlier than boys. To find them attractive is no problem in itself but to translate the perception of this attractiveness, by people in full adulthood, into sexual activity - which, possibly, may even be welcome - is a betrayal of responsible adulthood. Such adults are not paedophiles but hebephiles.
To the best of my knowledge, no other animal species has such a prolonged development process as homo sapiens - it is due to the size of our brains. It is to our credit that (unlike in previous times and also in some other cultures) we regard the completion stages of early adulthood as worthy of special consideration and protection.